Multi-stage energy absorber

Abstract

An energy absorbing liner system that offers a multi-stage reaction to impact and is positioned inside a member that receives an impact. The energy absorbing liner system has one or more interconnected energy absorbing modules that rebound after one or more impacts. At least some of the modules in the layer have a basal portion with multiple levels of reaction to impact. For example, a first stage has one or more membranes. A second stage has energy absorbing units with bendable walls. The membranes extend between the walls of adjacent energy absorbing units. The membranes alone or in combination with the side walls of the units at least partially cushion the blow in multiple stages of reaction by progressively absorbing energy imparted by an object that impacts the outer shell.

What is claimed is: 
     
       1. An energy absorbing liner system that is interposed between an incident surface that receives an impacting force and a mass to be protected from at least some of the impacting force, the energy absorbing liner system having
 one or more energy absorbing modules that offer a dual stage resistance to impacting forces, one or more of the energy absorbing modules having 
 a basal layer between the incident surface and the mass to be protected; 
 a first stage energy absorber extending from the basal layer toward the mass to be protected with one or more membranes that bend and /or collapse and have domed thin tops at least some of the membranes offering a first level of reaction to impacting forces that are low or high energy impact events normal to and inclined or tangential to the mass to be protected; 
 a second stage energy absorber extending from the basal layer toward the incident surface the second stage energy absorber having one or more energy absorbing units, the energy absorbing units extending from the basal layer the energy absorbing units having a wall with an upper perimeter proximate the basal layer, the energy absorbing units providing a second level of reaction to what remains of the impacting forces after at least partial absorption by the one or more membranes, the one or more energy absorbing units at least partially absorbing energy generated by an impacting object by the wall bending inwardly or outwardly or inwardly and outwardly without rupture, 
 ribs formed from the basal layer that extend between adjacent pairs of the energy absorbing units, the ribs forming a quadrilateral pattern, one of the membranes lying within the quadrilateral pattern; 
 and 
 wherein at least some of the membranes have a stiffness characteristic such that the second stage energy absorber is between 2 and 10 times stiffer than the membranes in the first stage, the first stage thereby at least partially absorbing low energy impacts and reducing shear and rotational forces experienced by the mass to be protected and thus providing an energy absorber that offers at least two levels of reaction to the impacting force. 
 
     
     
       2. The energy absorbing liner system of  claim 1 , wherein the incident surface that cooperates with the one or more energy absorbing modules in response to the impacting force is selected from the group consisting of a helmet, an automotive headliner, an anatomical member, a knee bolster, a bumper, a steering wheel, a knee pad, an elbow guard, a shoulder pad, an abdominal protector, a vehicular floor, a vehicular panel and a wrist pad. 
     
     
       3. The energy absorbing liner system of  claim 1 , wherein the one or more modules are made by a process selected from the group consisting of thermoforming, injection molding and combinations thereof. 
     
     
       4. The energy absorbing liner system of  claim 1 , wherein the wall of an energy absorbing unit defines a substantially frustoconical surface. 
     
     
       5. The energy absorbing liner system of  claim 1  wherein the wall of an energy absorbing unit has a lower edge proximate the incident surface that defines a lower perimeter, the lower perimeter defining a shape that is selected from the group consisting of a circle, an oval, an ellipse, an oblate oblong, a polygon, a quadrilateral with rounded edges and combinations thereof. 
     
     
       6. The energy absorbing liner system of  claim 1 , wherein at least some energy absorbing units have floors that are substantially flat and lie adjacent to the incident surface. 
     
     
       7. The energy absorbing liner system of  claim 1 , wherein the one or more energy absorbing units revert to or towards a pre-impact configuration after impact. 
     
     
       8. The energy absorbing liner system of  claim 1 , wherein the wall of an energy absorbing unit bends in response to impact and springs back to an un-deflected configuration in further response to impacting forces. 
     
     
       9. The energy absorbing liner system of  claim 1 , wherein at least some of the energy absorbing units have floors that are domed and extend towards the incident surface. 
     
     
       10. The energy absorbing liner system of  claim 1 , wherein at least some of the membranes are lacerated for added compliance.